Grain products such as wheat, barley, oats, sorghum, maize and oil seeds are usually treated prior to storage with a protectant solution. Diluted protectant concentrates are sprayed onto the product whilst it is being conveyed into storage, the solution being directed onto the product from a spray head which is located above the conveyor. The solution is pressurised and delivered to the spray head by a pump, and a solenoid actuated valve is provided for admitting the solution to the spray head when grain is sensed to be present on the conveyor. Sensing of the grain is effected by a hinged flap which is located in the conveyor path, the flap being caused to hinge upwardly when grain is present on the conveyor and the upward movement of the flap being used to cause actuation of the solenoid valve. The spray head is usually located upstream of the hinged flap and, thus, a small volume of grain passes the spray head before it is sensed to be present on the conveyor.
A number of problems arise from the use of the existing system. Firstly, even though low-toxic grain protectants may be used, there is a concern for the occupational health and safety of persons who are exposed to aerosol particles from the spray solutions in an enclosed work environment. Secondly, operator errors can occur when diluting chemicals with water. Thirdly, copious amounts of water are required for dilution. Fourthly, as in the case of most spray systems, the fine liquid droplets tend to be dispersed and it has been found that chemical losses of up to thirty per cent can be experienced. Quite apart from the increased operating costs that flow from these losses, the dispersion of spray may lead to inadequate dosing or, if overcompensation occurs, to excessive dosing of grain. Also, corrosion of plant and machinery may occur as a result of chemical dispersion into a closed environment.
The present invention seeks to overcome or diminish these problems by providing an arrangement in which a required fluid is supplied directly to a bulk commodity which is to be exposed to the fluid.